This invention relates to trench digging machines and, more specifically, to the removal of earthen type spoils brought from a trench by a trench digger to discharge such spoils laterally remote from the trench being dug.
In the art of trench digging machines, one form of trencher or trench digger employs a digger chain which is guided around the periphery of an elongated boom and driven by powered means on the vehicle which supports the trench digger. The boom carrying the chain is brought into engagement with the ground and by driving the digging chain around the boom periphery a trench is formed in the ground with the earthen type spoils brought out of the trench by the digging chain action requiring their removal to one or the other or both sides laterally of the trench being dug.
The prior art has recognized two primary types of spoils removal approaches, one employing rotating augers extending transversely to the plane of movement of digging chain on the boom and the other employing belt type conveyors to receive the spoils and transport them laterally to one or the other or both sides of the trench being dug. In either approach, the completed trench is left with an elongated pile of earthen type spoils extending parallel to the trench, available to be reintroduced into the trench once the desired pipe, cable, etc. has been placed in the bottom of the trench and is ready to be covered over.
There are different requirements for certain trenching operations. Whereas an auger type spoils removal approach is relatively simple and its driving power readily available from the drive for the digging chain, 29 Code of Federal Regulations Part 1926.651(i).sub.1 requires that the spoils be located more precisely, at least two feet, from the edge of the trench. A rotatable spoils auger is not as well adapted to achieving this more precise disposal from the edge of the trench and thus, a coveyor spoils removal system makes such precise lateral spacing simpler to accomplish. However, the cost of purchase and maintaining both a trench digger with an auger and one with a conveyor type spoils removal system adds substantially and prohibitively to the economics of being able to perform trenching operations within the various regulations for trenching and spoils disposal laterally at greater or lesser distances from the trench being dug.